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FI or carb - what would u do?

2K views 10 replies 8 participants last post by  hotrodg726 
#1 ·
So I'm swapping out the engine on my '55. Going from a 327 to a new 383. My dilemma is should I keep the fuel injection system that I had on the 327 or get a new carb. I currently have a Holley 4D system. Its old and hard to tune, but when you do finally get it set up, it works great. I'm updating the entire engine bay and want a clean look so all the wiring for the FI will have to go under dash. Car gets driven once or twice a month. So would you keep the fuel injection or sell it for the $500 they are currently going for and get a decent carb??? And no, my budget wont allow for a new fuel injection system..:)
 
#2 ·
I don't know anything about that Holley system but I will say that I will not put a carburetor on anything I own again. Port F.I. on everything for me.

That Holley system is a throttle body, correct? I don't know about those but had a friend take one off because it caused problems. If I were in your shoes and couldn't spring for a new MFI system, I'd probably go with a carb. Maybe a 700 cfm double pumper like the Holley 4778.
 
#5 ·
For a driver, a simple TBI system works great. I stick with GM factory based systems for reliabilty and parts availability.
The BBC throttle body is just about 700cfm so it's plenty for most mild builds.

MPFI is another good system but really only increases the wow factor when you pop the hood.

Most believe that it creates more HP and MPGs but in reality it was designed to improve the idle/low speed emissions due to the reduction of puddling in the intake runner at low rpms.

If you pull the same CFM and have the same timing and AFR then the HP really isn't going to change.

The GM TPI system was a good looking system that worked great for a standard daily driver that delivers good performance below 4000rpm. Anything above that and the TPI starts to go flat.

The older TBI actually had better low end torque numbers than the MPFI.

MPFI does give a little better instant throttle response or tip in due to the injector placement but it's not really anything you can quantify.

The year round driveability is drastically improved over the carb. It turns the old pushrod engines into a modern driver just like your wifes car. No more pumping the gas or sticky chokes or waiting for the engine to warm up before sticking it in gear.
Increased MPG is just a side benefit due to the O2 feedback to keep the AFR properly set all the time.
An added benefit is engine longevity due to no more washed or lean cylinders or fuel in the oil.

Bottom line, Carbs work...sometimes and none of them are "in tune" even 5 min after you get it off the dyno.

A good EFI will allow you to drive your classic anytime you want, any where you want and deliver the proper tune.
 
#6 ·
I pulled out the original FI system on my 57 Belair and went with natural aspiration. 650 CFM carb and matching manifold. I like the range of adjustment. Interesting that formula 1 cars are still naturally aspirated. Don't know how they pack it in, guess use turbo chargers.
 
#7 ·
Naturally aspirated means only with atmospheric pressure thus no turbo charger or super charger. It has nothing to do with FI or carburetor.
 
#8 ·
I don't know what a Holley 4D system is for sure, but if it's what I think it is and it's only worth $500 used, it's going to leave a lot to be desired.

Thing is, if your budget is really low, then you may be best off with a carb.

Lowest end I'd think would be a TBI system from a late 80s/early 90s truck or Caprice. Next step would be a TPI system from an 88-92 Camaro/Corvette. Both have limited power potential but good characteristics otherwise.

After that would be a FAST EZ system or Holley Terminator.
 
#11 ·
use the holley system you have. it is still way better than a carb. you already have it tuned so it will just need a few tweeks to be right.
 
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